Cam follower apparatus

Abstract

A cam follower apparatus includes at least a roller and a supporting shaft for supporting the roller freely rotatably. Unevenness is formed equally on the surface of at least one of the roller and supporting shaft by corrosion by manganese phosphate salt and the manganese phosphate salt film is formed on the corroded surface. Good-quality oil film can be formed stably without interruption thereof under even a strict working condition with a small amount of lubricant due to the unevenness formed on the film. Therefore, direct contact between metals is prevented, thereby improving lubricity.

What is claimed is: 
     
       1. A cam follower apparatus comprising: a roller;   a roller bearing;   a shaft, said shaft supporting the roller in a freely rotatable manner; and   wherein the surface of said roller is coated with a manganese phosphate salt film, said surface being changed to a form which includes uniformly concave parts, wherein the initial unevenness on the roller surface formed by machine processing is mutually independently constricted by the corrosive action of said film during the coating process, and convex parts having rounded tips, and said changed roller surface is coated with said film.   
     
     
       2. The cam follower apparatus according to claim 1 wherein said unevenness includes an area ratio on a cross section of the roughness center line of 30-40%, a position of the roughness center line is 1 μm or less from a top surface of the unevenness, an average diameter of the opening of a concavity in said unevenness on a section of said roughness center line is 55 μm or less, a depth of said concavity in said unevenness is more than 0.2 μm from said roughness center line, and the thickness of said film is 3-10 μm. 
     
     
       3. The cam follower apparatus according to claim 1, wherein said manganese phosphate salt film remains in the concave parts even after the convex parts on the roller surface dissipate by abrasion, said convex parts on the roller surface being exposed during use.